<template>
    <div class="header">
        <div class="header-abs"
             @click="bandleBackClick"
             v-show="showAbs"
        >
            <div class="iconfont detail-header-back">&#xe624;</div>
        </div>
        <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">
            <div class="iconfont header-fixed-back"
                 @click="bandleBackClick"
            >&#xe624;</div>
            景点详情
        </div>
    </div>
</template>

<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    bandleBackClick () {
      this.$router.push('/')
    },
    handleScroll () {
      const top = document.documentElement.scrollTop || document.body.scrollTop || window.pageYOffset
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = { opacity }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  mounted () {
    window.addEventListener('scroll', this.handleScroll)
  },
  destroyed () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>

<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    position absolute
    left .2rem
    top .2rem
    width .8rem
    height .8rem
    border-radius .4rem
    text-align center
    background rgba(0, 0, 0, 0.6)
    .detail-header-back
      font-size .48rem
      line-height .8rem
      color #fff
  .header-fixed
      z-index 2
      position fixed
      top 0
      right 0
      left 0
      height $headHeight
      line-height $headHeight
      text-align center
      color #fff
      background $bgColor
      font-size .32rem
      .header-fixed-back
        position absolute
        top 0
        left 0
        width .64rem
        text-align center
        font-size .4rem
        color #fff
</style>
